Dosimetry for Low Energy Electron Beam Applications at Fraunhofer FEP

Accelerating electrons to achieve chemical and biological effects is a well-established competence of Fraunhofer FEP. Today there is a wide variety of low-energy electron beam applications, ranging from seed dressing over inactivation of viruses for vaccines, to sterilization of medical devices. Moreover, there are new emerging technologies such as the stimulation of biological systems, electron beam sustained synthesis of chemical energy carriers, as well as the treatment of wastewater or exhaust gases with low-energy electrons. This spectrum of applications comes with a range of absorbed doses and calls for reliable, sensitive, and flexible methods for dosimetry.
Due to the limited penetration depth of electrons with energies of 300 keV and below, radiochromic films with thin active layers are suitable tools to measure electron dose distributions for the characterization and quality control of Fraunhofer FEP’s irradiation facilities. Risø B3 radiochromic film from DTU Health Tech [1, 2], the dosimeter of choice at FEP, reliably detects doses in the range of 10-100 kGy. However, with new upcoming applications, like bio-stimulation or wastewater treatment, doses in the single digit kGy range and even lower come to the fore. Hence, the palette of dosimeters at FEP must be extended. Gafchromic’s HD-V2 radiochromic film is a welcome complement and widens the accessible dose range down to 10 Gy [3].
Additionally, dosimeters based on the optically stimulated luminescence (OSL) of beryllium oxide offer a wide dose range and very high sensitivity [4-6]. They can be used to measure doses induced by X-ray components to gain more information about a specific radiation field. The paper gives an overview of the dosimetric practice of both radiochromic film and OSL dosimeters at Fraunhofer FEP based on selected examples of application.